Emma Watson, aka Hermione from the Harry Potter movies, shows up and steals supplies from James Franco and his friends, in the latest trailer for This is the End. But how did Rogen and his co-director/co-writer Evan Goldberg coax a crazy comedy performance out of Watson? And what sort of humor was going too far for this apocalyptic movie? We asked them, and they told us.

We caught up with Rogen and Goldberg for an exclusive interview at Wondercon over the weekend, and they told us everything we wanted to know about the apocalypse and celebrities.

What's more appropriate for the apocalypse: dick jokes or poop jokes? And why?

Goldberg: We recorded both...

Rogen: And people seemed to respond better to dick jokes.

Goldberg: We had to cut a lot of poop jokes

Rogen: America told us: "Dick jokes."

Why do you think America prefers dick jokes after the apocalypse?

Rogen: I think poop jokes are just too gross for people, honestly.

Goldberg: I personally don't love 'em.

Rogen: I think people are just grossed out by poop jokes. We saw first hand. We literally, in the movie we resort to drinking our own bodily — there's some drinking of our own pee, because we run out of water. And we filmed, we explored the idea on camera of eating our own poo, and there was a mass rejection.

Goldberg: It was like, the last day when everybody was having a good time, and they all got our jokes, and they all understood our humor.

Rogen: The crew were cool. We were friends with a lot of the people who worked on the movie, so they were very honest with us about how funny or not funny they thought what we were filming was at any given moment. And the way we filmed the poo thing, it was just me and Evan in a little room. With this confessional camera we had set up. We were alone in there...

Goldberg: We had microwaved a chocolate bar.

Rogen: We microwaved a chocolate bar, and it was like... [mimes eating]... and then I came out, and we were expecting the crew to be standing there laughing at the video monitors, and everyone was just like [mimes hanging his head].

Goldberg: And the DP, who has the exact same sense of humor as us, Brandon Trost, came up to us, and was like, "That wasn't cool."

Rogen: He was like, "That wasn't funny."

Goldberg: "Don't do any more of that."

Rogen: "There's no way you'll get any of that into the movie." So the answer is: Dick. Not poo.

Goldberg: Dick, not poo.

Rogen: That's our motto.

So how hard was it to bring out the weirdo in Emma Watson? And how weird was it working with Rihanna?

Rogen: The answer for both was, not very.

Goldberg: The thing was, once you got to the set, there was like ten of us. And there's a vibe when you have ten different actors who are all working together, and all the producers all knew the actors. So you kind of like were coming to a summer camp that was already in session, and they just kind of slid right into it.

Rogen: Emma thought it was super funny what we were doing, and she was really funny. And Rihanna was awesome. She was great. She improvised. She did some stuntwork that she didn't think she was going to be doing. [Laughs] And it was great. It was really easy. There were some days where I looked around, and there's like 20 movie stars on the set right now, and everyone was kind of coexisting in a great way. It was almost like no-one wanted to be the asshole, because there were so many people there that you didn't want to be the one who was the fucking asshole.

Goldberg: Hearing you say that, I'm picturing one of them acting up, and it would have been a disaster for them. Everybody would have just zoned in on them.

Emma Watson, though, seems to have less of a comedy background than most of the people in the movie. How did she adjust?

Goldberg: She definitely, for the first half of her first scene, was unsure of how it was going to go. But once she got it, she just dove in hard, and was improv-ing like the rest of the guys, and doing all of that good stuff.

Rogen: And she's like... one of her jokes in the movie is like, so funny, and it's a pretty edgy joke. And it's awesome, how she played it.

Do you think there's a certain amount of wish fulfillment in seeing famous people get killed?

Rogen: Probably. To some degree. [Laughs]

Goldberg: I think it's like wish fulfillment people didn't even know they had.

Rogen: I didn't know I had it until I saw. [Laughs] But yeah, I think there is some... I don't know why.

Goldberg: Also, when they get hurt. You're like, "That's not just a character. That's Craig Robinson. And I know who that is. And it makes you care a little more, and laugh a little more."

Rogen: It makes it that much more absurd in a way, that it is these people, and these terrible things are happening to them. You know? I don't know if people like it because it's the people getting hurt, but I think people definitely have a very big reaction to seeing these very graphic things happen to these very famous people. As themselves, especially. It's fun. It's nice. Honestly, they react exactly how we hoped they would.

Besides the poop jokes, with the apocalypse, was there material that was too horrifying or too upsetting, that you had to back away from?

Goldberg: Just the poop stuff. That's really the answer.

Rogen: We kind of tried to delve into the darker elements a little bit. But again, it's a comedy. It's not that dark a movie. But I think we explore a lot of the themes that you would expect to find in one of these types of movies. We probably have two more dick jokes than The Road.

What can you tell me about Cannibal Santa?

Rogen: Oh yeah. That's written on IMDB [on the cast list]. I can't tell you what Cannibal Santa is! I actually let that go, just to see if anyone would notice. All I will say is, there is a character in the movie called Cannibal Santa, but I'm not going to tell you what he does. But he's there, and that's not a typo.

Is there something about bromance that's stronger than the end of days?

Goldberg: What's bromance? [Laughs]

Rogen: I don't know. For the sake of comedy, we make it that way. But I don't know if in real life, it has any bearing. I mean, this is a movie about a lot of dudes, and it's a movie about the inner dynamics of a large group of friends. So I think in this movie, we definitely explore how the power of bromance collides with the power of the apocalypse. The fact that I just said the word "bromance" so many times makes me want to kill myself.

Goldberg: We never attach that word to us.

It took decades to go from the classic Westerns to Blazing Saddles. Do you think there's a similar process with apocalyptic movies?

Rogen: Maybe. I think our movies are somewhat... I don't want to say they're making fun of the genres they're in, but they're kind of commenting on them in a way. And I think, like, the more familiar people are with the conventions of these types of movies, the easier it is for us to play off those expectations and make jokes about them, and stuff like that.

Goldberg: A few countries won't get each of our movies.

Rogen: For us, anyway, it's easier to make a type of movie like this now that there's so many movies like this happening. Because it just makes it funnier, honestly. The more movies like this, the more our jokes are funny, because we're kind of playing off of the expectations that you have for a movie like this. You know?

But do you think it's doing something similar to what Blazing Saddles did with westerns?

Rogen: Hey, if you want to compare us to Mel Brooks, I'll take it. [Laughs]

Goldberg: It is exactly like Blazing Saddles. [Laughs] If you like Blazing Saddles, you will love this movie. [Laughs at the absurdity of that statement]